CN102776532A - Method for preparing ultrafine zinc powder by adding aluminum-containing compound alkaline liquor through electrolysis - Google Patents

Abstract

The invention belongs to the field of high-tech production of ultrafine powder and relates to a method for preparing ultrafine zinc powder. The method comprises the following steps of: (1) mixing distilled water, strong base and a zinc compound to prepare solution; (2) adding an aluminum-containing compound into the solution prepared in the step (1), stirring and dissolving; (3) inserting an electrode plate into electrolyte prepared in the step (2), and carrying out electrolytic reaction; and (4) stopping electrolysis, immediately taking out the zinc powder, washing the zinc powder with water and ethanol, and drying to obtain the ultrafine zinc powder with metallic luster. The zinc powder has the small particle size of 2-7mu m and high grade; and the current density, the scraper frequency and the addition are controlled, so that the zinc powder with the metal zinc content of over 97 percent can be obtained, and a primary zinc powder standard is achieved. The process control is simple, the ultrafine zinc powder is produced through a one-step method, and the electrolytic liquid waste is recycled to realize zero release.

Description

A kind of method of adding aluminum contained compound alkali lye electrolytic preparation super-fine zinc dust

Technical field

The invention belongs to the superfine powder production field, relate to a kind of preparation method of super-fine zinc dust.

Background technology

Super-fine zinc dust is meant the zinc powder of granularity below 10 μ m; Because its unique physicochemical property; Have broad application prospects in fields such as Chemical Manufacture, slip additive, coating, high performance electrode materials, super-fine zinc dust has become one of focus of countries in the world scientific worker research.The national demand of super-fine zinc dust is at present greater than 100,000 tons/year, and cumulative year after year, and price is common zinc powder price 3-4 times.At present, maximum industry that super-fine zinc dust is used still is a coating and anticorrosion, can make zinc-rich paint or directly is plated on the preservative coat.The zinc powder particle diameter is tiny more, and surfactivity is big more, helps the formation of coating.

The preparation method of zinc powder mainly contains distillation method, atomization, high-energy ball milling method, electrolytic process and vacuum-evaporation-condensation method both at home and abroad.Wherein the zinc powder particle diameter of atomization preparation is more than 10 μ m, thereby can not prepare super-fine zinc dust.The production efficiency of distillation method is high, but the super-fine zinc dust activity that makes is lower.The super-fine zinc dust that high-energy ball milling method makes is a flakey, but is prone to pollute.

The technology that proposes among Chinese patent CN1450182A and the CN1482263A has promoted the scale operation of alkaline process electrolytic zinc powder technology; But the zinc powder particle diameter that this flow process is produced is bigger than normal, and thickness is inhomogeneous, and the preparation super-fine zinc dust needs to grind with ball mill; Energy consumption is high, complex process.China 201210034534.7, through the zinc powder that added lead-containing compounds refinement preferably, but the problem that also exists micro-scorification to go out.

Summary of the invention

The objective of the invention is to provide a kind of preparation method of super-fine zinc dust for the defective that overcomes prior art.This method provides a kind of granularity little, and is active high, and the super-fine zinc dust one-step method production process that purity is high utilizes this method to produce super-fine zinc dust, and production cost is low, and energy consumption is little, and flow process control is simple.

For realizing above-mentioned purpose, the present invention adopts following technical scheme:

The present invention can realize the single stage method direct production of super-fine zinc dust.Add aluminum contained compound, promoted the catholyte degree of polarization on the one hand, help fine particle and separate out; On the other hand, increase electrolytic solution viscosity, suppressed foreign ion and separated out, improved the pure grade of zinc powder.Aluminium exists with the meta-aluminic acid radical ion in alkaline electrolyte simultaneously, can electrolysis not separate out.

A kind of preparation method of super-fine zinc dust comprises following steps:

(1) zero(ppm) water, highly basic and zn cpds are mixed and made into solution;

(2) in the solution of step (1) preparation, add aluminum contained compound, and stirring and dissolving, make electrolytic solution;

(3) insert battery lead plate in the electrolytic solution that in step (2), makes, carry out electrolytic reaction, and wipe the zinc powder that electrolysis goes out at any time off;

(4) stop electrolysis after, take out zinc powder immediately, after the cleaning, drying promptly obtains the super-fine zinc dust of metalluster.

The particle diameter of described super-fine zinc dust is 2-7 μ m.

Described zn cpds is ZnO or ZnCO ₃In one or both.

Zinc content is 15-60g/L in the middle mixture solution of described step (1).

Highly basic in the described step (1) is NaOH or KOH, preferred NaOH, and wherein the content of highly basic in mixing solutions is 150-250g/L.

Described aluminum contained compound is NaAlO ₂, Al ₂O ₃, AlCl ₃, Al ₂(SO ₄) ₃Or Al ₂(CO ₃) ₃In one or more.

Aluminium content in the described step (2) in the electrolytic solution is 10-200mg/L.

Battery lead plate in the described step (3) is to be positive plate with the stainless steel plate, and the magnesium plate is a negative plate, and current density is 500-1500A/m ², interpole gap is 1-10cm, and whole electrolytic process carries out in a groove, and electrolyte temperature 15-80 ℃, electrolysis time is 5-120min, and wherein stainless steel is preferably 304 stainless steels, 321 stainless steels or 316L stainless steel.

Water and absolute ethyl alcohol flushing zinc powder in the described step (4), first water cleans residual NaOH, shows neutral to washing fluid, with the residuary water on the absolute ethyl alcohol flushing zinc powder, suppresses the zinc powder surface oxidation again.

Drying in the described step (4) is vacuum-drying or dries up with nitrogen.

The present invention is through discovering: when electrolysis contains the zinc basic soln, adds suitable aluminum contained compound, can the refinement zinc powder, and zinc powder grade rising simultaneously.

After electrolytic solution added aluminum contained compound, polarization was strengthened, and the cathodic deposition overpotential strengthens.According to following formula, overpotential increases, and has increased nucleation rate, the refinement zinc powder.

${\mathrm{\η}}_d=E_r-E_{\mathrm{ir}}=\frac{\mathrm{RT}}{\mathrm{ZF}}\ln \frac{C_o}{C_s}$

$\frac{C_s}{C_o}=1-\frac{i_d}{i_{\mathrm{dl}}}$

${\mathrm{\η}}_d=\frac{\mathrm{RT}}{\mathrm{ZF}}\ln \frac{i_{\mathrm{dl}}}{i_{\mathrm{dl}}-i_d}=\frac{\mathrm{RT}}{\mathrm{ZF}}\ln \frac{1}{1-\frac{i_d}{i_{\mathrm{dl}}}}$

$i_{\mathrm{dl}}=\frac{{\mathrm{ZFDC}}_o}{\mathrm{\δ}}$

$D=\frac{\mathrm{KT}}{6\mathrm{\πr\η}}$

The factor of visible influences precipitation process comprises: each ionic concn, activity quotient and normal potential and overpotential or the like in industrial application, the concentration of additive, exist form and reaction conditions all can have influence on electrolytic process.

Adding the Trace Aluminum ion among the present invention, is example with 20mg/L, because viscosity raises, limited by limit current density Jd, and the impurity that electrolysis is separated out (is example with lead) is minimum to the influence of zinc powder purity.

$J_d=\frac{\mathrm{nFDc}}{\mathrm{\σ}}$

$\mathrm{\ω}\left(\mathrm{Pb}\right)=\frac{J_{d}M\left(\mathrm{Pb}\right)}{J\left(Z_n\right)M\left(Z_n\right)\mathrm{\η}}$

From theoretical calculation analysis, trace mineral supplement can electrolysis go out the one-level zinc powder.After aluminum contained compound is dissolved in electrolytic solution, changed SOLUTION PROPERTIES, influenced the zinc powder deposition, product purity strengthens.

The present invention is following from the process method that the direct electrolysis production super-fine zinc dust of strong base solution that adds aluminum contained compound is adopted: at first use zero(ppm) water, highly basic and zn cpds are processed mixing solutions, make to contain zinc 15-60g/L, contain NaOH150-250g/L; Add aluminum contained compound then, and stirring and dissolving, be made into and contain aluminium 10-200mg/L electrolytic solution; In gained electrolytic solution, insert battery lead plate, stainless steel plate is a positive plate, and the magnesium plate is a negative plate, and current density is 500-1500A/m ², interpole gap is 1-10cm, and whole electrolytic process carries out in a groove, and electrolyte temperature 15-80 ℃, electrolysis time is 20-120min; Electrolysis finishes, and takes out zinc powder rapidly, and water, absolute ethyl alcohol clean, and vacuum-drying or dry up with nitrogen promptly obtains the super-fine zinc dust of metalluster.

The present invention is an additive with the aluminum contained compound, and a kind of method from the direct electrolysis production super-fine zinc dust of strong base solution is provided, and has the following advantages and beneficial effect:

(1) technical process of the present invention is simple, and process is easy to control is convenient to scale operation.

(2) additive can not separated out at negative electrode, and zinc powder is of high grade.

(3) process solution reusable edible, no waste liquid effluxes.

(4) zinc powder particle size that goes out of electrolysis is little, and specific surface is big, and is active high.

Description of drawings

Fig. 1 embodiment of the invention electrolytic deposition zinc powder sem photograph.

Embodiment

Further specify the present invention below in conjunction with embodiment, but the invention is not restricted to embodiment.

Embodiment 1

(1) use zero(ppm) water, sodium hydroxide and zinc oxide are processed mixing solutions, make to contain zinc 30g/L, contain NaOH225g/L;

(2) add NaAlO then ₂With Al ₂(SO ₄) ₃Mixture make electrolytic solution contain aluminium 20mg/L electrolytic solution;

(3) in gained electrolytic solution, insert battery lead plate, 304 type stainless steel plates are positive plate, and the magnesium plate is a negative plate, and current density is 1000A/m ², interpole gap is 3cm, and whole electrolytic process carries out in a groove, and 30 ℃ of electrolyte temperatures, electrolysis time are 60min, and wipe the zinc powder that electrolysis goes out at any time off;

(4) take out zinc powder immediately after electrolysis finishes, and water, absolute ethyl alcohol clean, vacuum-drying or dry up with nitrogen promptly obtains the super-fine zinc dust of metalluster.

The super-fine zinc dust current efficiency 98.55% that present embodiment makes, metallic zinc content 98.87% reaches one-level zinc powder standard.The product size-grade distribution (is seen table 1) as follows, length mean diameter 6.59 μ m, the particle above 50% surpasses 90% particle less than 13 μ m (>, 600 orders less than 5.64 μ m).Accompanying drawing 1 is the sem photograph of electrolytic part zinc powder.Can find out the existence of Al, hinder the zinc particulate and grown up, play refinement particulate effect.

Table 1

Sreen analysis	MV (um)	Variance (um)	D10(um)	D50(um)	D90(um)
						The length mean diameter, D [1,0]	6.59	7.79	0.76	5.64	12.82
Surface area mean diameter, D [2,0]	10.88
						The specific surface area mean diameter, D [3,2]	26.41	17.19	7.79	22.85	53.13
Volume mean diameter, D [3,0]	37.6

Embodiment 2

(1) use zero(ppm) water, sodium hydroxide and zinc carbonate are processed mixing solutions, make to contain zinc 15g/L, contain NaOH180gL;

(2) add aluminum oxide and aluminum chloride mixture (1:1) then, make electrolytic solution, electrolytic solution contains aluminium 200mg/L;

(3) in gained electrolytic solution, insert battery lead plate, 321 type stainless steel plates are positive plate, and the magnesium plate is a negative plate, and current density is 500A/m ², interpole gap is 8cm, and whole electrolytic process carries out in a groove, and 75 ℃ of electrolyte temperatures, electrolysis time are 20min; , and wipe the zinc powder that electrolysis goes out at any time off;

(4) electrolysis finishes, and takes out zinc powder rapidly, and water, absolute ethyl alcohol clean, and vacuum-drying or dry up with nitrogen promptly obtains the super-fine zinc dust of metalluster.

The super-fine zinc dust that present embodiment makes records current efficiency 92.64%, metallic zinc content 97.53%.Particle size analyzer records the product size-grade distribution, and the length mean diameter is 5.79 μ m, and surface area mean diameter 8.96 μ m surpass 90% particle less than 11 μ m (>, 800 orders) (specifically seeing table 2).

Table 2

Sreen analysis	MV (um)	Variance (um)	D10(um)	D50(um)	D90(um)
						The length mean diameter, D [1,0]	5.79	6.84	0.58	4.06	10.76
Surface area mean diameter, D [2,0]	8.96
						The specific surface area mean diameter, D [3,2]	24.53	16.08	6.96	21.02	38.54
Volume mean diameter, D [3,0]	12.54

Embodiment 3

(1) use zero(ppm) water, sodium hydroxide and zinc compound (zinc oxide mixes with zinc carbonate 1:1) are processed mixing solutions, make to contain zinc 60g/L, contain NaOH250g/L;

(2) add aluminum oxide and aluminium carbonate mixture (1:1) then, make electrolytic solution, electrolytic solution contains aluminium 80mg/L;

(3) in gained electrolytic solution, insert battery lead plate, 316L type stainless steel plate is a positive plate, and the magnesium plate is a negative plate, and current density is 1500A/m ², interpole gap is 1cm, and whole electrolytic process carries out in a groove, and 15 ℃ of electrolyte temperatures, electrolysis time are 120min; , and wipe the zinc powder that electrolysis goes out at any time off;

(4) electrolysis finishes, and takes out zinc powder rapidly, and water, absolute ethyl alcohol clean, and vacuum-drying or dry up with nitrogen promptly obtains the super-fine zinc dust of metalluster.

The super-fine zinc dust that present embodiment makes records current efficiency 96.76%, metallic zinc content 96.85%.Particle size analyzer records the product size-grade distribution, and zinc powder length mean diameter is 3.06 μ m, and surface area mean diameter 3.59 μ m surpass 90% particle less than 6 μ m (specifically seeing table 3).

Table 3

Sreen analysis	Size(um)	STD(um)	D10(um)	D50(um)	D90(um)
						The length mean diameter, D [1,0]	3.06	1.87	0.62	2.78	5.67
Surface area mean diameter, D [2,0]	3.59
						The specific surface area mean diameter, D [3,2]	5.02	1.68	2.78	5.09	7.4
Volume mean diameter, D [3,0]	4.01

Table 1-3 data presentation is added aluminum contained compound and can be made the zinc powder median size less than 10 μ m, and the addition of aluminium can significantly impact the particle diameter and the pattern of zinc powder; When aluminium addition during at 10-100mg; Along with addition increases, the zinc powder refinement is obvious, at 100-200mg; Increase addition, grain diameter influence diminishes to zinc powder.Show that from morphology analysis this technology zinc powder erosion resistance is strong, size-grade distribution is concentrated.

The above-mentioned description to embodiment is can understand and use the present invention for ease of the those of ordinary skill of this technical field.The personnel of skilled obviously can easily make various modifications to these embodiment, and needn't pass through performing creative labour being applied in the General Principle of this explanation among other embodiment.Therefore, the invention is not restricted to the embodiment here, those skilled in the art are according to announcement of the present invention, and not breaking away from the improvement that category of the present invention makes and revise all should be within protection scope of the present invention.

Claims (10)

1. the preparation method of a super-fine zinc dust is characterized in that: comprise following steps:

(1) zero(ppm) water, highly basic and zn cpds are mixed and made into solution;

(2) in the solution of step (1) preparation, add aluminum contained compound, and stirring and dissolving;

(3) insert battery lead plate in the electrolytic solution that in step (2), makes, carry out electrolytic reaction;

(4) stop electrolysis after, take out zinc powder immediately, after the cleaning, drying promptly obtains the super-fine zinc dust of metalluster.

2. preparation method according to claim 1 is characterized in that: the particle diameter of described super-fine zinc dust is 2-7 μ m.

3. preparation method according to claim 1 is characterized in that: described zn cpds is ZnO or ZnCO ₃In one or both.

4. preparation method according to claim 1 is characterized in that: zinc content is 15-60g/L in the middle mixture solution of described step (1);

Or the highly basic in the described step (1) is NaOH or KOH, preferred NaOH, and wherein the content of highly basic in mixing solutions is 150-250g/L.

5. preparation method according to claim 1 is characterized in that: described aluminum contained compound is NaAlO ₂, Al ₂O ₃, AlCl ₃, Al ₂(SO ₄) ₃Or Al ₂(CO ₃) ₃In one or more.

6. preparation method according to claim 1 is characterized in that: the aluminium content in the described step (2) in the electrolytic solution is 10-200mgL.

7. preparation method according to claim 1 is characterized in that: stainless steel plate is a positive plate in the described step (3), and the magnesium plate is a negative plate, and current density is 500-1500A/m ², interpole gap is 1-10cm, and whole electrolytic process carries out in a groove, and electrolyte temperature 15-80 ℃, electrolysis time is 20-120min.

8. preparation method according to claim 7 is characterized in that: described stainless steel is 304 stainless steels, 321 stainless steels or 316L stainless steel.

9. preparation method according to claim 1 is characterized in that: water and absolute ethyl alcohol clean zinc powder in the described step (4); Specifically be first water flushing residual NaOH, show neutral, again with the residuary water on the absolute ethyl alcohol flushing zinc powder to washing fluid.

10. preparation method according to claim 1 is characterized in that: the drying in the described step (4) is vacuum-drying or dries up with nitrogen.

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